Field
The disclosed and claimed concept relates generally to electrical interruption equipment, and more particularly, to circuit interrupters and electrical enclosures which resist installation of a main circuit interrupter having a given current carrying rating from being installed in an electrical enclosure having a current rating less than the given current carrying rating.
Related Art
Electrical interruption equipment is well known for use in any of a variety of electrical applications in order to protect circuits or portions of circuits from certain predefined conditions. The predefined conditions can include overcurrent conditions, undervoltage conditions, fault conditions, and other conditions. Such electrical interruption equipment can include circuit interrupters such as circuit breakers, vacuum interrupters, and the like, and can further include electrical enclosures such as breaker panels, load centers, switchgear enclosures, and the like within which the circuit interrupters can be installed.
In certain applications such as domestic applications and other applications, the electrical interruption equipment may include an electrical enclosure that receives a main current feed and that distributes current to various other smaller circuits. Each such smaller circuit typically is protected by its own circuit interrupter having an appropriate current carrying rating. Such circuit interrupters are often installed in slots on the electrical enclosure and connect with one or more electrical bus bars within the electrical enclosure to provide current to the individual circuits. Such circuit interrupters are typically intended to individually trip in certain predefined circumstances in order to protect the corresponding circuit from any of the aforementioned predefined conditions.
The electrical interruption equipment in such an application typically additionally includes a main circuit interrupter that is interposed between the main current feed and the bus bars and is intended to trip and thus interrupt the flow of current to the bus bars if the overall current draw of all of the circuits combined exceeds a given current level and/or in other circumstances. Such a main circuit interrupter typically is selected to have a current carrying rating no greater than the current rating of the electrical enclosure. That is, the current flowing through the bus bars to the individual circuits results in I2R heating of the bus bars and other components, and an electrical enclosure thus has a current rating which should not be exceeded. This is in order to avoid possible damage to the electrical interruption equipment and possible injury and/or property destruction. The main circuit interrupter is thus typically selected to have a current carrying rating no greater than the current rating of the electrical enclosure, meaning that the main circuit interrupter will interrupt the current flow to the bus bars if the aggregate current flowing through the individual circuits that are connected with the bus bars reaches the current rating of the electrical enclosure. By way of example, a given electrical enclosure may have a current rating of 200 Amps, and it may have connected therewith various circuits that are protected by circuit interrupters mounted on the electrical enclosure and that may have current carrying ratings such as 15 Amps, 20 Amps, 30 Amps, 50 Amps, and the like depending upon the characteristics of the circuit. The aggregate current capacity of all of the various circuits combined (i.e., by adding together all of the various current carrying ratings of all of the circuit interrupters connected with the individual circuits) often exceeds the current rating of the panel because it is expected that fewer than all of the protected circuits will be simultaneously carrying their maximum current, such as in the way an electrical resistance furnace and an air conditioner would typically never be simultaneously operated even though they may be connected via separate individual circuits interrupters with the same load center.
While such electrical interruption equipment has been generally effective for its intended purposes, it has not been without limitation. Many of the circuit interrupters, including the main circuit interrupters and the individual circuit interrupters that are connected therewith, look very similar to one another. Even though the current carrying rating of a given circuit interrupter is typically clearly printed on the circuit interrupter itself, a possibility exists that a circuit interrupter, such as a main circuit interrupter having a current carrying rating that is less than or greater than what was intended to be used, can be connected with a given circuit such as between the main current feed and the bus bars of the electrical enclosure. An erroneous installation of a circuit interrupter having a current carrying rating less than what had been intended does not typically result in a meaningful concern of equipment damage or injury, apart from the fact that it may trip more often than is appropriate. Such frequent tripping might occur because the loads connected with the circuit interrupter may have been designed to draw relatively higher current and to be protected with a circuit interrupter having a greater current carrying rating than the erroneously installed circuit interrupter. However, the erroneous installation of a circuit interrupter having a current carrying rating greater than the protected circuit or the electrical enclosure itself can be problematic because the erroneously installed circuit interrupter does not trip when the current flowing through the connected circuit exceeds that for which it was originally designed. Such a situation can undesirably result in a potential for equipment damage, property destruction, and personal injury. It thus would be desirable to provide electrical interruption equipment that avoids such a possibility.